壳聚糖-丙烯酰胺接枝共聚物的制备及其絮凝性能

采用水浴加热,硝酸铈铵为引发剂,氮气保护体系,引发壳聚糖(CS)与丙烯酰胺(AM)接枝共聚反应,制得接枝共聚物P(CS-AM).探索了接枝共聚反应的合成条件对产物特性黏度的影响,确定了最佳反应条件为m(CS):m(AM)=1:4、w(CS+AM)=20％、w(硝酸铈铵)=0.09％、反应温度45℃、体系pH=3.采用红...     

淀粉接枝丙烯酰胺的合成及其絮凝性能的研究

以玉米淀粉(St)和丙烯酰胺(AM)单体为原料,采用过硫酸钾引发剂合成了淀粉接枝丙烯酰胺共聚物(St-g-AM)。用红外光谱对接枝共聚物进行了结构表征,用粘度法测定了分子量。讨论了聚合反应的各个因素对接枝共聚反应的影响,考察了接枝共聚物的絮凝性能。结果表明,以接枝效率为考察目标,其最佳的合成工艺为:引发剂的浓度为0.07 g/100 mL,淀粉与丙烯酰胺的质量比为1∶2.2,反应温度为65℃,反应时间3 h。淀粉接枝丙烯酰胺共聚物比430万分子量的聚丙烯酰胺(PAM)对高岭土水样的絮凝性能更好,当接枝共聚物的投加量为6 mg/L时,对高岭土水样的浊度去除率达到81.77%。最佳条件所合成出的淀粉接枝丙烯酰胺的分子量为75万。     

微波辐射下壳聚糖-丙烯酰胺接枝物的合成及其絮凝性能研究

以硝酸铈铵作为引发剂、丙烯酰胺为单体,用微波辐射法合成了壳聚糖-丙烯酰胺接枝共聚物。通过正交试验考察反应条件对接枝率和接枝效率的影响,得出最佳工艺条件为:反应时间12 min,引发剂浓度5 mmol/L,丙烯酰胺和壳聚糖质量比5:1,反应温度40℃。最佳条件下接枝率和接枝效率分别达到148.6%和44.0%。壳聚糖接枝物与聚丙烯酰胺(PAM)对高岭土悬浮液的絮凝对比试验表明:在酸性条件下接枝物与PAM的絮凝效果相近;在中性和碱性条件下接枝物的絮凝性能优于PAM。     

壳聚糖-甲基丙烯酰氧乙基三甲基氯化铵接枝共聚物的制备与絮凝性能研究

以壳聚糖和甲基丙烯酰氧乙基三甲基氯化铵(DMC)为原料,硝酸铈铵为引发剂,Span-20为乳化剂,通过反相乳液聚合技术,合成了壳聚糖-DMC接枝共聚物。通过正交试验考察了反应条件对接枝度的影响,得出的最佳工艺条件为:反应时间5 h、引发剂浓度16 mmol/L、壳聚糖与DMC质量比1:6、油水体积比1:1。最佳条件下平均接枝度达到110 %。将得到的壳聚糖接枝共聚物用作絮凝剂处理高岭土悬浮液,结果表明其絮凝性能优于壳聚糖和聚丙烯酰胺(PAM),且在pH值6.0、投加量为2.0 mg/L时絮凝效果最佳。     

宽絮凝窗口壳聚糖改性物脱除石油污水乳化油的研究

以壳聚糖(CS)、丙烯酰胺(AM)和甲基丙烯酰胺丙基三甲基氯化铵(MAPTAC)为原料,通过低压紫外引发接枝共聚合成壳聚糖基阳离子絮凝剂CS-g-P(AM-MAPTAC),并用于石油污水乳化油的脱除。利用FT-IR、HNMR、SEM等对CS和CS-g-P(AM-MAPTAC)进行表征。结果表明,CS-g-P(AM-MAPTAC)的接枝率可控,其最佳制备条件为:光引发剂质量分数为0.3%、总单体质量分数为7.5%、单体质量比为25%、总单体与壳聚糖质量比为4、光照时间为120 min。同时,考察了絮凝剂用量、pH、初始油质量浓度和接枝率对CS-g-P(AM-MAPTAC)絮凝性能的影响。结果表明,与CS和市售阳离子聚丙烯酰胺(CPAM)相比,CS-g-P(AM-MAPTAC)具有更优异的絮凝性能,在初始油质量浓度为550～2 200 mg/L和p H为6～10时,除油率达到95%,表现出更宽絮凝窗口。     

引发方式对接枝改性壳聚糖结构和絮凝性能的影响

以丙烯酰胺(AM)、二甲基二烯丙基氯化铵(DMDAAC)为接枝共聚单体,分别采用热引发、光引发和超声波引发方式制备壳聚糖基絮凝剂CS-P(AM-DMDAAC)。采用红外光谱和扫描电镜(SEM)对三种不同引发方式制备出的絮凝剂进行表征。以高岭土模拟水样为处理对象,采用三种絮凝剂进行絮凝实验,结果表明光引发下制备产品的絮凝效果要明显优于其它两个产品,同时分析了出现这一现象的原因。     

改性壳聚糖絮凝剂的制备及絮凝性能的研究

以过硫酸铵为引发剂,在壳聚糖与丙烯酰胺的质量比为1∶2的条件下,使壳聚糖和丙烯酰胺在30℃时发生接枝共聚反应,制得改性壳聚糖絮凝剂(CAM),通过对高岭土悬浮液和印染废水的絮凝实验表明,CAM具有阳离子型高分子絮凝剂的典型特征,其絮凝性能优于壳聚糖,在其用量为壳聚糖质量的20%情况下,CAM对印染废水的CODC r去除率提高了30%。     

淀粉-聚丙烯酰胺接枝共聚物的工艺优化与性能研究

通过玉米淀粉接枝聚丙烯酰胺(PAM)制成了新型复合絮凝剂S-g-PAM,进行了影响接枝共聚物合成的单因素实验和正交实验,以对高岭土悬浊液的絮凝性能为评价指标。结果表明,最佳合成条件为,m(玉米淀粉)∶m(PAM)=3∶0.001(质量比),NaOH∶NaOCl=2∶3(体积比),反应时间40 min,反应温度30℃,对高岭土溶液(110NTU)最佳去浊度效果为97%,投加量为30 mg/L。S-g-PAM使用的pH值范围为8~10,最佳温度范围20~40℃,与其它絮凝剂相比,其絮凝效果较好。     

阳离子聚合物P(AM-DBC)的合成及絮凝性能研究

以丙烯酰氧乙基二甲基苄基氯化铵(DBC)和丙烯酰胺(AM)为原料,通过水溶液自由基聚合法制备了一种阳离子聚合物P (AM-DBC),研究了反应温度、单体物料配比以及引发剂用量等因素对反应转化率和除油率的影响,并通过絮凝实验评价了该阳离子聚合物的除油率和絮凝性能.结果 表明:在反应温度为65℃、挖(DBC) ∶n (AM) =1∶3、引发剂过硫酸盐占单体DBC和AM总质量的2.5‰、链转移剂占单体DBC和AM总质量的1‰、反应时间为7h条件下,转化率(实际产量占单体理论转化量)为96.3％.与常规絮凝剂聚丙烯酰胺(PAM)和P(AM-DM)相比,P(AM-DBC)的除油率和絮体状态较好,且和无机絮凝剂复配后处理效果更佳.     

疏水改性阳离子胶原蛋白絮凝剂制备条件优化

以皮革废弃物提取的明胶为原料,丙烯酰胺(AM)、丙烯酰氧乙基三甲基氯化铵(DAC)和丙烯酸丁酯(BA)为单体[n(AM)∶n(DAC)∶n(BA)=80∶18∶2],叔丁基过氧化氢和焦亚硫酸钠为引发剂,接枝共聚合成了疏水改性阳离子胶原蛋白絮凝剂P(C-AM-DAC-BA)。以絮凝剂对油田模拟废水浊度的去除率为指标,探讨了明胶与单体的质量比、引发剂浓度、接枝温度、接枝时间对絮凝效果的影响。通过响应面法优化得到了P(C-AM-DAC-BA)接枝共聚最佳条件为m(明胶)∶m(单体)=1∶2.04、引发剂浓度0.032 mol/L、接枝温度49℃、接枝时间2.8 h。在该条件下,P(C-AM-DAC-BA)对油田模拟废水浊度去除率为91.5%。     

Eigenspectra for flocculation quality estimation

We present an image analysis algorithm for flocculation quality estimation in high-solids slurries, and demonstrate its performance using inline process images of oil sands tailings flocculation. While a skilled human operator can often successfully evaluate such images, variations in feed as well as the lack of isolated flocs or spatial reference-points inherent in a high-solids slurry can cause conventional image analysis techniques to fail. We overcome these challenges by recasting the images in Fourier space, discarding phase information, and applying an eigenfaces-inspired image recognition algorithm to the resulting spectra. Each image is represented using a few projection coefficients onto an orthogonal basis and evaluated using likelihood-based classification schemes. This algorithm shows a high degree of success evaluating the flocculation quality of 129 batch and inline flocculation experiments (5,610 images total) utilizing feed tailings from two different oil sand producers at a variety of feed dilutions and flocculant dosing levels.     

Orthokinetic flocculation of latex microspheres

Orthokinetic flocculation of pvc latex microspheres (approx. 1 μm) was studied in a mini-couette apparatus with laminar velocity gradients up to 10 s^?1 . Measurements with a Coulter Counter showed the growth of up to 1600-fold aggregates. Flocculation in a fixed porous bed indicated some aggregate formulation but the results were masked by a pronounced filter effect. Fluidised bed flocculation in both single pass and recycle stages showed very significant particle aggregation.     

Modelling PCC flocculation by bridging mechanism using population balances: Effect of polymer characteristics on flocculation

A population balance model for flocculation of PCC particles with polyelectrolytes of very high molecular weight, medium charge density and different degree of branching is presented. The model considers simultaneously aggregation, breakage and flocs restructuring to describe the PCC flocculation by bridging mechanism. The maximum collision efficiency factor, a parameter related with the fragmentation rate and a time constant for flocs restructuring have been taken as fitting parameters. These fitting parameters are optimized to get the best fit between experimental data obtained by LDS in a previous study and the modelled results. The optimized parameters were correlated with flocculant concentration, flocs structure and polymer branching. The correlations obtained show well the effects of flocculant concentration, flocs structure and polymer structure on the flocculation kinetics and flocs restructuring which are translated in the model parameters. Moreover, the flocs break up due to polymer degradation was introduced in the model by decreasing, with time, the maximum collision efficiency factor. It was shown that this effect can be neglected since the improvement in the results is too small relatively to the high increase of the computational time required to perform the simulation.     

微生物絮凝剂的絮凝特性研究

从活性污泥中分离出1株产高效絮凝剂微生物AspergillusM-25,利用其发酵液进行絮凝特性实验。实验结果表明:(1)该絮凝剂对250μm,4g/L,pH为7的高岭土悬浊液有良好的絮凝效果,絮凝率>97%;(2)菌株M-25产生的活性成分95%存在于上清液中,只有约5%存在于洗涤后的菌细胞中,未接种的培养液中不含絮凝成分;⑶影响生物絮凝剂絮凝效果的因素主要有絮凝剂的投加量,高岭土悬浊液的pH、浊度、粒度以及金属离子的添加;⑷利用该生物絮凝剂处理活性炭粉末溶液和土壤悬浊液,也取得较好的处理效果,显示了絮凝范围的广泛性。     

Study on chain deformation of polyacrylamides in solutions and its flocculation performance during the flocculation process

Effects of external conditions, solution concentration, solvent quality, added salt, and pH on the chain conformation dimension of two kinds of polyacrylamide (PAAm) flocculants, neutral‐PAAm, and cationic‐P(AAm‐DMC) (DMC, 2‐[(methacryloyloxy)ethyl] trimethylammonium chloride), in parent solutions and their flocculation performance for Kaolin suspensions have been investigated by Ubbelohde viscometer and spectrophotometer, respectively. It was found that a negative correlation existed between the flocculation performance of PAAm flocculants and their chain sizes in parent solutions. This was attributed to the expanded chain deformation of PAAm flocculants during the flocculation process from the flocculant parent solution to the Kaolin suspension and was interpreted in term of the competitive interaction among the polymeric flocculant, solvent, and Kaolin particle in the chain deformation process. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

紊流絮凝动力初探

根据紊流水力特征研究絮凝动力学问题,分析絮凝动力因素,得出了主要作用力及主导作用力。认为紊流运动可以看成是各种不同尺度的涡旋运动迭加于平均速束的结果,涡旋运动产生的剪切力和离心惯性力是絮凝颗粒产生接触碰撞的主要作用和,而涡旋剪切力是絮凝反应的主导动力。为提高絮凝效率提供了技术途径。     

机械絮凝和网格絮凝处理低浊度水源水的性能对比中试研究

针对某市第三水厂的三期工程建设,用中试规模试验来选择絮凝方式。试验结果表明,在相同的源水、相同加药量和相同的进水量的情况下,网格絮凝的沉淀效果优于机械絮凝。随着PAC投加量的增加,沉淀出水的浊度和大于2μm的颗粒数呈下降趋势。源水水质和投药量是影响沉淀池出水水质的最重要因素,最佳投药量的范围为21~28mg/L。     

The strength of aggregates formed in flocculation

Three distinct techniques have been employed to determine the strength of adhesion of particles in coagulating and flocculating media. Adhesion forces ranging over 4 orders of magnitude were measured with spherical particles of glass (10–30, μm dia.) in aqueous solutions containing varying concentrations of magnesium sulphate and an anionic polyacrylamide flocculant.Measurements of floc size distribution of suspensions subjected to known rates of shear were made in a specially designed rotating concentric cylinder apparatus.In general, a clear correlation was observed between particle adhesion and floe size, provided the chemical and physical conditions were comparable. Effects of particle size and “ageing” were also studied.     

聚硅酸锌的絮凝作用研究

以聚硅酸(PSA)、硫酸锌为原料制备了系列无机高分子絮凝剂聚硅酸锌(PSZn).测定了其电荷特性.采用Si-Mo逐时络合比色法分析了Zn2 对PSA的形态分布的影响.初步试验了PSZn对模拟水样的絮凝效果.结果表明,加入硫酸锌有效地改善了PSA的电中和能力,对其形态分布有一定的影响.与PSA相比,稳定性和除浊效果均有明显的提高.